1. Field of the Invention
The present invention relates, generally, to nozzles for conducting and expelling a fluid stream and dispersing and/or mixing same within an ambient fluid; and, more especially, to such a nozzle including a resiliently flexible tube which serves as the discharge member. The nozzles of the present invention are particularly well adapted for use in the injection of a fluid within an air treatment apparatus such as a wet scrubber or the like; but also have diverse applications in the mixing or other interaction of fluids and fluid streams regardless of the environmental setting.
2. Description of the Background Art
The present inventor's related, copending applications Ser. Nos. 336,762 (now abandoned) and 773,416 disclose and claim a wide range of air treatment apparatus for conditioning an effluent stream, which apparatus include one or more fluid injection nozzles comprising a length of resiliently flexible tubing, such as elastomeric tubing, for the introduction of a conditioning agent to a treatment zone of the device. Those nozzles overcome many of the inherent problems historically experienced in respect of wet scrubbers, among which may be mentioned high operation costs in order to achieve fine enough fluid dispersion, nozzle plugging, and the related inability to recirculate efficiently the conditioning agent. Attention is invited to those related applications for greater elucidation upon those and other advantages of the nozzles disclosed and claimed therein.
Numerous, diverse types of treatment apparatus have been devised over the last several decades for the conditioning of effluent streams, and particularly gaseous effluent streams, generated during industrial processes. A principal impetus for the development and use of such devices has arisen as a consequence of environmental conscientiousness in an effort to abate pollution. Thus, myriad designs have been proposed for the classification of particulate, the elimination of toxic, noxious or malodorous constituents, or the alteration (actual or perceptual) of the constituents of an effluent before it is released to the atmosphere. Experience has shown that the need to meet ever-increasing standards imposed upon those who must discharge an effluent to the atmosphere has resulted in the need to resort to very complicated, and hence expensive, machinery.
Various types of devices have been utilized to classify, segregate, or otherwise remove particulate material from a gaseous effluent stream. Conventionally, cyclone separators, electrostatic precipitators, so-called "bag houses" and plenum scrubbers have been employed for this task. Each type of device offers some advantage over the others but each has important limitations from either operational or cost-effectiveness points of view.
Conventional cyclone separators work fairly well for the classification of particles having nominal sizes greater than about 25-30 microns. As the particulate to be removed falls within progressively lower size ranges, the effectiveness of a conventional cyclone separator falls off precipitously. Typically, for particles less than about 10-15 microns, a normal cyclone separator is found to be virtually ineffectual. Yet, it is currently envisioned that particles an order of magnitude smaller (e.g., aerosols) will require removal from effluent generated during various industrial processes.
Some have attempted to improve the ability of a cyclone to classify smaller particulates by the injection of fluid agents within the treatment zone of the device. The normative wisdom in this regard indicated that the fluid would effectuate an increase in the mass of smaller particulate, thereby increasing the apparent size thereof insofar as classification is based upon centrifugal separation which, in turn, is directly related to the mass of the particulate to be classified. But, such prior attempts have normally diminished the overall operational efficiencies of the cyclone since the fluid injection has resulted in a diminution in field or kinetic energy of the vortical flow of effluent-entrained particulate. By and large, therefore, there has been no development of commercially-acceptable wet cyclone devices.
Electrostatic precipitators are viewed to work very well for removing small particulate from an effluent gas stream. Nonetheless, complete commercial integration of electrostatic precipitators as a uniform mode of air treatment to remove particulate is unlikely to occur since these devices are quite expensive and, thus, cost-prohibitive for many applications. To a lesser extent, but equally applicable, are the sometimes prohibitive costs involved in the installation of bag houses.
Another approach for particulate removal is by means of a plenum scrubber. These devices rely upon the expansion of the effluent stream by introducing the flowing stream into a large chamber. The accompanying pressure drop tends to strip particulate from the effluent. Oftentimes, fluid treatment agents are caused to pass in counter-current relationship vis-a-vis the direction of effluent flow. These devices are fairly efficient within fairly confined limits.
Packed bed scrubbers have offered another option for effluent treatment; that effluent passing through a bed of, e.g., spherical elements typically bearing a liquid treatment agent injected within the device. The packing increases the available surface for interactive contact between agent and effluent to be treated thereby. A problem customarily encountered in operation of these scrubbers is plugging within the bed due to particulate in the effluent lodging within interstices in the packing, leading to channeling and then dramatic diminution in scrubber efficiency. Somewhat related, at least in a conceptual sense, to packed bed scrubbers are fluid solid scrubbers such as those used in the treatment of effluent emanating from sewage treatment operations and in the treatment of stack gases emitted from oil or fossil-fired plants to remove sulfur dioxide therefrom. In the former case, activated carbon particle beds are utilized whereas the latter employ, for example, calcium carbonate or like ores. Activated carbon beds are both inefficient and very expensive to operate. The carbon materials require regeneration after relatively short cycling times or complete replacement. Operational costs can be high, considering the fact that some devices require pressure drops of six inches of water or more to drive the effluent through the bed. The scrubbers utilized to remove sulfur dioxide from stack gases routinely are extremely large devices, a requirement made necessary in order to achieve adequate residence time of the effluent in proximity of the treating ore (e.g., calcium carbonate).
Further along these lines, not infrequently it is mandatory both to remove particulate and also to remove or treat undesirable fluid or gaseous components entrained within an effluent stream. Customarily, regardless of the device employed for conditioning the effluent, suitable chemical agents are included within a fluid caused to contact or otherwise interact with the effluent. Gases may be reacted for removal or adsorbed or absorbed on or within a liquid treatment agent. Fluids may likewise be reacted, mixed, coagulated, or otherwise altered sufficiently to effectuate removal from the effluent.
A persistent difficulty heretofore experienced in respect of the injection of fluid treatment agents within an air treatment apparatus results from limitations inherent in the fluid injection devices employed. Quite routinely, fluid treatments agents, which usually must be finely dispersed to be optimally effective, are introduced via nozzles such as sintered nozzles having relatively small fluid passages. Other approaches, which attempt to minimize the need to use these fairly expensive nozzles, nonetheless typically require discharge orifices of relatively small size in order to insure adequate atomization or dispersion of the fluid treatment agent. Virtually all such approaches result in the use of fluid injection nozzles highly prone to plugging if even very small size foreign particulate finds its way within the fluid distribution system. This has all but eliminated the ability to use conventional filtration as a means for permitting recirculation of treatment fluid. Thus, the approach typically employed is to meter as best as possible the theoretical, optimum amount of treatment agent for reaction with the components in the effluent to be removed without including any excess. While this may seem fine on paper, in a plant many problems may be faced. If less than an appropriate amount of agent is injected into the air treatment apparatus, there will be incomplete reaction with the constituents to be removed and, accordingly, discharge of untreated effluent. If one attempts to compensate to insure virtually complete reaction, there is characteristically added an excess of agent which cannot be recovered and reused, contributing to an increased cost of operation and, perhaps, contributing to other sources of potential pollution since the remaining active components usually cannot simply be discharged to a sewer system. Even in cases where the conditioning agent is simply water, the copious quantities required in many installations ultimately results in considerable difficulties respecting waste water disposal as recirculation may not be an effective expedient.
Insofar as the present invention advantageously merges the concepts of certain prior art nozzles, adapting same specifically for use in conjunction with effluent treatment apparatus to overcome operational problems of the nature aforesaid and incorporating modifications to extend the operational utilities thereof, some background on the characteristics of these nozzles is appropriate. The class of nozzles involved are those which dispense a pressurized fluid, typically a liquid, through a flexible tube. As pressurized fluid flows through the tube and discharges therefrom, a reactionary force is felt within the tube wall. By carefully mating the wave mechanics of the flowing fluid with the mechanical properties of the flexible conduit, a standing or resonant flexural vibrational wave may be established in the tube itself.
This phenomenon has been recognized in various prior art devices where the flexural vibration of a tube is employed to some beneficial end. For example, irrigation or lawn sprinklers have been devised which rely on an oscillatory motion of a flexible tube when pressurized water discharges therefrom. Exemplary of such devices are those disclosed in U.S. Pat. No. 141,632, No. 3,030,031 and No. 2,930,531. This general principle has also been applied to the atomization of a liquid, and a representative device for this purpose is disclosed in U.S. Pat. No. 3,123,302. Other nozzles where a spray is created by conveying a pressurized fluid through a flexible tube are disclosed in U.S. Pat. No. 2,417,222 and No. 2,758,874. The latter of these two patents is further noteworthy insofar as it discloses a means for controlling the spray by including an outer sleeve on the flexible tube which may be slid along the length thereof. A dishwasher making use of these types of nozzles is the subject of U.S. Pat. No. 2,977,963.
The flexible injection nozzles of the present inventor's copending application Ser. Nos. 336,762 (now abandoned) and 773,416 have been found to be advantageously implemented in association with various types of air treatment apparatus and eliminate the historical impediments to the efficient removal of particulate for treatment of effluent in a wet scrubber device. The rapid oscillatory motion of the resonating flexible tube and fine dispersion of fluid issuing therefrom has been found to provide excellent coverage of effluent to be treated, while physical characteristics of the tube allow for virtually plug-free operation permitting recirculation of treatment fluid; all of which advantages contribute not only to the efficiency of treatment but permit dramatically reduced operating costs. Notwithstanding the acclaim accorded the devices which are the subject of the aforenoted application, continuing investigations have led to the recognition that other features in the operation of these types of nozzles may well be desirable depending upon the demands of a given task at hand. For example, the desire is not recognized to provide a tailored discharge tube to control the gross spray pattern (as distinguished from the dispersion spray pattern) by controlling the surface described by the resonating flexural tube. The ability to recirculate treatment fluids without elaborate filtration has led to the recognition of a desire to accommodate very large particulate material which may have a dimensional aspect greater than the fluid bore of the resilient discharge tube. In situations where the treatment fluid (whether liquid, gas or mixtures thereof) is introduced within a principally gaseous environment such as the case in the treatment of a gaseous effluent within a wet scrubber, it has been recognized that a desire exists either to replace or augment fans which drive the effluent stream. In like vein, where the pressurized treatment fluid is introduced into a principally liquid ambient, a desire is recognized for some means to replace or augment the requirement of, e.g., a mechanical mixer. It is also deemed desirable in the context of gaseous effluent treatment to introduce that effluent and the treatment agent therefor to the conditioning apparatus (e.g., plenum) as an intimate admixture thereof, a particularly beneficial goal where aerosols must be removed.